nbc's martin fletcher is in tel aviv where air raid sirens were heard this morning. >> reporter: lynn, good morning. following up on netanyahu's threat. overnight 30,000 reserves were given potential order to report for duty overnight 16,000 soldiers were told, reserve soldiers, were told to report to their units. they will be joining army units that massed on the border of gaza. armored personnel carriers, hundreds of thousands of troops ready for ground invasion. as you suggested in introduction, a show of force or the real thing?